The man from Northern Virginia, accused of killing his wife, used a BDSM-themed dating site to attract an unsuspecting participant in his plan to eliminate his spouse, according to his au pair partner and co-defendant.

Juliana Peres Magalhães, a Brazilian au pair employed by both suspect Brendan Banfield and victim Christine Banfield, revealed to prosecutors that he chose murder over divorce while they engaged in an affair.

“And so I asked him, ‘Are you going to divorce her?’” Magalhães recounted to prosecutors on October 25, 2024, in footage shared by NBC Washington on Tuesday.

“And then he replied, ‘That’s not my plan.’ He further explained that he was considering a method to remove her from the equation.”

Brendan Banfield proceeded to FetLife.com — a platform for BDSM and fantasy interactions — where he set up a fraudulent profile, posing as Christine Banfield, in search of someone to fulfill a rape fantasy by visiting her home in Fairfax County, according to Magalhães.

This tactic is how he allegedly ensnared Joseph Ryan, 39, who thought he was in contact with Christine Banfield but was actually communicating with Brendan Banfield or Magalhães, as stated by prosecutors.

They set up Ryan to come to the Banfield home with a knife to attack Christine, who was there alone while Brendan Banfield and Magalhães were nearby, prosecutors said.

“We told him before that it was kinda part of the game, where the person gets in the bedroom and then I would act like scared, like, try to run or try to scream or if the person starts doing something, she would just get kinda freaked out and try to resist but it was like ‘part of the game,’” Magalhães said.

The staged attack gave Brendan Banfield and Magalhães the opportunity to murder Christine and then kill Ryan in a phony act of self-defense, prosecutors said.

Magalhães pleaded guilty to manslaughter for her role in the double-slaying.

Brendan Banfield is accused of fatally stabbing his wife and shooting Ryan.

The plot was months in the making with Brendan Banfield going as far as installing new, sound-cancelling windows at the home-turned murder scene, according to Magalhães.

The au pair even recalled testing the sound one day.

“And then I went outside in the driveway and he went up to the bedroom, and then he started like screaming and yelling to see if I could like hear anything outside,” she said.

“I couldn’t really hear, like, much.”

Brendan Banfield is set to go on trial in October, while Magalhães is expected to be sentenced after that.

Brendan Banfield’s attorney could not be immediately reached for comment on Wednesday.